In-line roller skates typically comprise a boot, a frame, and a plurality of rollers or wheels mounted to the frame which are "in-line" (i.e., in serial longitudinal alignment held by transversely-disposed axles). The frame has a pair of spaced-apart downwardly extending sidewalls which define a wheel cavity, which receives the wheel axles and from which the partially recessed wheels downwardly extend. The frame also includes a boot-engaging structure positioned on top of the frame, typically comprising a toe plate and heel plate. As will be discussed below, the frame is important because it affects the strength, durability, and performance of the skate.
In-line skating has become extremely popular in both aggressive sport activities such as hockey and racing, as well as for exercise or leisure type recreational skating. Especially important for aggressive sporting activities is an in-line skate's ability to sustain shocks and perform well (and reliably) under highly stressed conditions such as sharp turns, jumps, sudden stops and even abrupt contact with hard surfaces. For example, when in-line roller skates are used by hockey players, conventional light weight frames can be bent or fractured when struck by a hockey stick, the hockey puck, another skate, or even the enclosed playing arena wall when "slammed" by another player. The sidewall components of the frame that form the wheel cavity are the most exposed and therefore most susceptible to such damage. The materials and designs of skate components have become very specialized as the number of varieties of activities have expanded. For example, on many skates the optimum wheel size varies as a function of the sport or activity for which the skate is used. As another example, many recently developed frames are formed out of a single thin piece of lightweight material that minimizes overall skate weight, thereby reducing the fatigue experienced by the skater.
If a sidewall on a conventional in-line roller skate having a one-piece wheel frame is damaged, the sidewall alone cannot be replaced; instead, the entire frame must be replaced. Disadvantageously, presently available frames are typically quite expensive due to both material and labor costs (i.e. the costs associated with casting or machining a single-piece frame and the high price of the light weight materials used to construct these frames). In addition, skaters who use their skates for several different activities also face frame replacement difficulties, as a separate frame is often required to accommodate the different sized wheels that provide optimum performance for each different activity.
In-line roller skates including multiple-piece frames have been described in the prior art, as evidenced, for example, by the skate designs disclosed in U.S. Pat. No. 5,277,437 to Moats, U.S. Pat. No. 4,666,169 to Hamill et al., and U.S. Pat. No. 4,418,929 to Gray. As such, these designs permit the replacement of damaged sidewalls without the replacement of the entire frame. However, these frames use sidewalls that include cross-members or other lateral projections to provide rigidity and strength to the frame. Increased strength improves the durability of the frame, while increased rigidity can improve skate responsiveness. Including such lateral projections necessitates either machining or separately casting each sidewall in the manufacturing process, and thus the cost of manufacturing an individual sidewall can be quite high. An additional disadvantage of these multi-piece frame configurations is that their sidewalls are configured for a specific side of the skate; thus, it is necessary to have both a left and right spare sidewall available.
Several additional difficulties with presently available in-line roller skate frames relate to the impact that performance-enhancing design modifications have had on the skate's durability and manufacturing cost. For example, frame configurations such as the skate disclosed in U.S. Pat. No. 5,092,614 to Malewicz proposed to have improved skate performance by decreasing the weight of the frame. However, modifying the frame to decrease weight generally decreases the strength and durability of the frame, increases the cost of producing it or both. Similarly, almost all conventional frames include lateral cross members that increase the skate's rigidity to provide for desired increased speed and responsiveness. However, as described above, forming sidewalls that include such cross-members requires additional machining or casting which can significantly affect the cost of the skate frame.
One solution is offered in co-pending and co-assigned U.S. patent application Ser. No. 08/573,660, filed Jan. 17, 1995, which discloses an in-line skate frame which has side walls that are devoid of any lateral projections. The side walls are positioned laterally of and rest against flanges extending downwardly from the heel and toe plates. However, the heel and toe plates are joined to the sidewalls with fasteners that protrude laterally beyond the sidewalls. This configuration can create stress points and reduce handling characteristics of the skates. Exposure of the protruding fasteners also makes then more susceptible to causing or incurring damage.